Rising atmospheric levels of CO2 will lead to foods that are lower in vital nutrients such as zinc and calcium. The poorest countries will be hardest hit, increasing inequalities yet further.
“This is a huge problem already,” says Christopher Weyant of Stanford University in California. “Rising CO2 leads to a substantial increase in the disease burden.”
For decades, biologists have been growing plants in high levels of CO2 to see how it affects them. These studies show that while higher CO2 levels can boost yields of some – but not all – crops, they also reduce the levels of some nutrients.
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In a high CO2 world, every serving of bread, pasta, fruits and vegetables delivers more starch and sugar but less calcium, magnesium, potassium, protein and other essential nutrients – including iron and zinc.
To estimate the impact, Weyant first used data on dietary patterns from 137 countries to work out the existing disease burden from zinc and iron deficiencies. He measured this in terms of disability-adjusted life years, or DALYs.
One DALY can be thought of as one lost year of “healthy” life, according to the World Health Organization.
Lost years of life
If the nutrient content of food remained unchanged, iron and zinc deficiencies would be expected to induce 1073 million DALYs globally between 2015 and 2050, his team’s model suggests.
But decreasing zinc and iron level in foods due to rising CO2 will induce an extra 126 million DALYs globally over this period – a rise of 12 per cent.
And this is under a moderate scenario for CO2 emissions. “It could be worse if CO2 rises higher,” says Weyant. It might also likely be worse if the study included the effect of all the other missing nutrients.
The study also does not take account of the fact that rising temperatures and changing rainfall patterns will affect food production.
“The negative effects of extreme weather and climate events on production can result in rapid food and cereal price increases, reducing access to food, particularly among the poor,” says Kristie Ebi of the University of Washington in Seattle
One way to combat dietary deficiencies is to create new plant varieties. Researchers have already genetically modified many crops to make them richer in key nutrients. For instance, in 2016 a team based in the Philippines announced they had created .
However, opposition to GM crops has made it very difficult to get these crops out of the lab and into the hands of farmers. A vitamin A-enriched rice called Golden Rice has been in development for decades
Read more: Hidden cost of climate change is unwanted carbs in your food
